MPEG Surround (MPS) is an audio codec for coding a multi-channel audio, such as a 5.1 channel and a 7.1 channel. The MPS may compress and transmit a multi-channel audio signal at a high compression ratio.
Only, MPS has a constraint of backward compatibility in encoding and decoding processes. Thus, a bit stream of the multi-channel audio signal via MPS requires the backward compatibility that the bitstream is reproduced in a mono or stereo format even with a previous audio codec.
Accordingly, even though a number of channels of the multi-channel audio signal to be input to the MPS increases, a finally output and transmitted audio signal needs to be represented in mono or stereo. A decoder may reconstruct the multi-channel audio signal from an audio bit stream using additional information received from an encoder. Here, the decoder may reconstruct the multi-channel audio signal based on the additional information for upmixing.
However, a communication environment is improved in recent years and a transmission bandwidth is increased such that a bandwidth allocated to the audio signal is also increased. Accordingly, technology has been improved in a direction of maintaining an original sound quality of the multi-channel audio signal more than of excessively compressing the multi-channel audio signal to correspond to the bandwidth. Nevertheless, compression is still required to process the multi-channel audio signal having a large number of channels.
Thus, even though the number of channels increases, a method of reducing and transmitting a volume of data through compression greater than or equal to a predetermined level while maintaining a quality of the multi-channel audio signal is required.